Cutting tools for shredding materials usually have a rotary body structure formed with essentially axially extending grooves into which cutter bits, for example in strip form, can be inserted. They are held in the groove by suitable clamping arrangements The cutter bits should be replaceable since they wear. Usually, the direction of the cutter bits or strips is slightly inclined with respect to the axis of rotation of the tool, for example by about 2.degree. to 3.degree..
The cutter bits or strips are usually made of ceramic, such as stellite, a hard metal, such as tool steel or the like. These cutter bits or strips are highly stressed, particularly when comminuting or granulating plastic materials which include fillers. The cutter elements must be replaceable so that, when worn, they can be exchanged or re-sharpened.
A cutting tool for granulated plastic material is shown in German Patent 34 39 029 (to which European Published Application 182 037, Fritsch and Hench, corresponds). Clamping arrangements located at the circumference of the tool body are provided. The tool body has longitudinal grooves which define oppositely located clamping surfaces. In the bottom or root region, the cutter elements have suitable clamping surfaces, for example in form of an essentially V-groove, which are in engagement with the clamping surfaces, for proper orientation and matching force transferring fit. The clamping arrangement further includes balls which are radially clamped by the V-surfaces of the tool body.
The clamping arrangement for the cutter strips thus is highly effective, and provides for interlocking interengagement holding of the cutter strips; yet, difficulties arose upon exchange of the cutter elements in the field, since the balls could get lost and could fall out of the groove upon exchange of cutter strips.
It has also been proposed, see Published European Patent Application 85 111 989, to replace the balls by essentially cylindrical clamping sleeves which are formed with a slit extending over a portion of their length and which, in the region of their bore, are formed with interior conical or wedge-like clamping surfaces which engage against a clamping screw which is threaded into the bore of the sleeve. This, also, is an effective clamping system for the cutter strips. It is, however, quite difficult to tighten and, after tightening, to release the clamping strips. The screwing-in and screwing-out of the threaded screws is comparatively time-consuming, complex, and must be carried out carefully and hence requires skilled operators and careful attention to the task.